尝试创建一个函数,然后在F#中通过"not that function"过滤序列

Question

我的数据是SEQUENCE:

[(40,"TX");(48,"MO");(15,"TX");(78,"TN");(41,"VT")]

我的代码如下:

type Csvfile = CsvProvider<somefile>
let data = Csvfile.GetSample().Rows

let nullid row = 
    row.Id = 15

let otherid row =
    row.Id= 40

let iddata = 
   data
   |> Seq.filter (not nullid)
   |> Seq.filter (not otherid)

我创建了这些功能.

然后我想调用那些函数的"not"来将它们从序列中过滤掉.

但问题是我在前两个函数中遇到"row.Id"错误,因为你只能用一个类型来做.

我如何解决这个问题,以便我能成功地解决这个问题.

我的结果应该是SEQUENCE:

[(48,"MO);(78,"TN");(41,"VT")]

Answer 1

您可以使用>>operator来组合这两个函数:

let iddata = 
   data
   |> Seq.filter (nullid >> not)
   |> Seq.filter  (othered >> not)

请参见函数组合和流水线.

或者你可以使它更明确:

let iddata = 
   data
   |> Seq.filter (fun x -> not (nullid x))
   |> Seq.filter  (fun x -> not (othered x))

你可以看到它在行动:

let input = [|1;2;3;4;5;6;7;8;9;10|];;
let is3 value =
    value = 3;;

input |> Seq.filter (fun x -> not (is3 x));;
input |> Seq.filter (not >> is3);;

他们都打印 val it : seq<int> = seq [1; 2; 4; 5; ...]